The statements in the background of the invention are provided to assist with understanding the invention and its applications and uses, and may not constitute prior art.
A hopper car is a type of railroad freight car used to haul bulk commodities such as coals, fertilizers, grains, and iron ores. A hopper car may be covered or open on top, and discharges its load through doors located on the underside of the car body. Automatic unloading of materials from a hopper car may be facilitated at designated dumping sites, where an electric current collector shoe or pickup shoe may slide over an energized trackside conductor rail to operate an electro-pneumatic control valve to open and close discharge doors.
One issue in hopper car design is in the sealing mechanism of bottom discharge doors. As bulk commodities are generally pelletized, granular, or particulate, poor sealing performance of a discharge door device may cause material leakage onto rail tracks, resulting in economic loss, adverse effects to drainage of the track bed, and possible environmental pollutions. Such effects are especially severe when materials are transported over long distances under various weather conditions.
Another issue in hopper car design is safety considerations for operations in confined dumping spaces such as buildings, unloading sheds, and grain elevators. Conventional bottom discharge hopper cars use pick-up shoes that slide across an electrified conductor rail to transmit electrical signals to the control valve, for automatically opening and closing one or more bottom discharge doors. When a tight, direct contact between a pick-up shoe and the conductor rail is lost, for example due to dirt or leaves on the rail, an electric arc may jump across the gap, creating sparks that can in turn ignite a fire or explosion within a confined space if dusts or similar combustible particulate materials are present in high-enough concentrations. As a result, unloading of hopper cars often occur in vented open spaces outside of processing and storage facilities.
Therefore, in view of the aforementioned difficulties, it would be an advancement in the state of the art to provide railroad hopper car designs with durable and long-lasting discharge doors and/or pick-up shoe arrangements and actuating assemblies that mitigate or prevent hazardous dust explosions.
It is against this background that the present invention was developed.